Weight balancing mechanism



June 1940- C. SARBER 2,205,671

WEIGHT BALANCING MECHANISM Filed Aug. 1, 1938 3 z f5 v i a Z;

WI -LL.

11v VENTOR [7'62 5ar 11 A z rolezws ys Patented June 25, 1940 WEIGHTBALANCING l Ira c. Sarber, Elkhart, Ind, assignoruto Finnell System,Inc., Elkhart, Ind; a corporation of Indiana Application August 1, 1938,Serial No. 222,431 1 I Claims.

This invention relates'to weight counterbalancing devices particularlysuitable for floor scrubbing machines. i

The main objects of this invention are to provide an improvedcounterbalancing device adapted to maintain a substantially constant oruniform pressure on the bristles of a floor scrubber regardless of theamount of wear of the bristles; to provide a weight counterbalancingdevice which is of simple construction and free of mechanical troublessoas to give 'satisfactoryservice over a long period of time; and toprovide a weight counterbalancing device which is readily adjustable toaccommodate varying conditions and specified requirements. I

An allustrative embodiment of this invention is shown in theaccompanying drawing, in which:

Fig. 1 is a fragmentary view, partly in elevation and partly in section,of a floor scrubbing machine equipped with the improved weight balancingunit.

Fig. 2 is an enlarged sectional view, taken on the line 2-2 of Fig. 1,looking in the direction indicated by the arrows.

Fig. 3 is a fragmentary view showing one arm of the bell crank and itsaxis of pivotalsupport with relation to the center from which thearcuate cam slot therein is formed.

In the construction of power driven floor scrub so bing machines, it hasbeen found most satisfactory to build the electric driving motor andgear freely swingable in a vertical plane. In this ma nner, the floorscrubbing brushes are maintained in contact with the floor at all timesregardless of the unevenness thereof.

However, in the manufacture of the larger sizes of floor scrubbingmachines, an electric motor of considerable size and weight is requiredorder to have suflicient power for rotating the relatively large scrubbrush unit. The weight of such a heavy motor and gear box, restinguponthe bristles. of the scrubbing brushes, has a tendency to bend them overand therefore the necessity has arisen for providing the motor and brushunit with suitable counterbalancing means which will tend to relieve thebrush bristles of a portion of their load and at the same time permit" arequired weight or pressure thereon so as to secure an effective anddesirablescrubb ing action of the brush bristles.

In other words, scrubbing brushes'of this character do not operate tothe best advantage if too much weight is placed thereon. On the otherhand,-there must be enough weight on the bristles to cause them toperform and work in an efficient manner. Furthermora'provision must bemade for automatically maintaining this desired amount of weight uponthe brush bristles as the s PATENT OFFICE.

bri stleswear away and become shorter during long periods of use.

In the construction shown in the drawing, the 'front end of afloorscrubbing machine frame In is shown provided with a wheel or roller l I,which is adapted to rest upon and traverse/the floor being scrubbed, thewheel ll being journaledon a shaft 12. The shaft l2 also pivotallysupports the rear'end of a forwardly extending arm l3, the front endofwhich is rigidly attachedto an electric'moto'r 14, so as to be freelyswingable in a ver tical plane. The motor I4 is provided with a gearreduction case [5 rigidly connected thereto, which, through suitablereduction gears, not shown, permits the motor M to rotate a verticallydisposed shaft [6 which depends from theunder side of the gear box l5.

Thelower end of the driving shaft I6 is con-I ll andmountings for thebrushes l8"are shown in the 'co-pending application of Walter S.Finn'ell, Serial No. 211,633, filed June 3, 1938, and

assigned to the assignee of the present invention. Means are providedfor partially counterbalancing the weight of the motor l4 and itsunitary reduction gear and case and comprise a bell crankjmember'generally designated 20, which-is pivotally supported on a pin 2|so as to swing in a 'verticalplane parallel tothe plane'of movement ofthe motor and brush unit. The pin 2| is rigid- 1y mounted-at itsopposite ends at the top end of an upstanding'bracket 22, the lower end23 of which is'welded or otherwise rigidly secured to a forwardlyextending arm 24 of the frame 10.

The bell crank 20 is provided with two arms, one 1 of which, 25, isprovided with a transversely extending conical shaped aperture 26through which extends one end of a rod 21. The end of the rod 21extending therethrough is provided with a semi-spherical head 28 whichrests against the topsurface of the arm 24 and permits limited swingingmovement of the rod 21 within the conical shaped aperture 26. The otherend of the rod 27 is threaded into one end of a turnbuckle 29, the otherend of which threadably receives one end of a rod 30. The other end ofthe rod 30 is pivoted at 3| in an upstanding clip 32 which is rigidlysecured to the top of the motor M. The two rods 21 and 30 with theconnecting turnbuckle 29 provide an adjustable link connection betweenthe bell crank arm 25 and the motor and brush unit.

The other arm 33 of the bell crank member 2|] is provided with anarcuate slot 34, the radius of which is taken from a center point offsetwith respect to the axis of pivotal movement of the bell crank, i. e.,offset with respect to the axis of the bell crank pivot pin 2|, as shownmost clearly in Fig. 3 of the drawing, thus forming a cam slot.

The slot 34 receives and the side walls thereof snugly embrace a roller35 which is journaled on one side of and at the top end of asubstantially vertically disposed rod 36. The rod 36 extends through anaperture in the top end of an inverted cup shaped cylindrical member 37which houses a helical compression spring 38. One end of the compre sionspring 38 bears against the under side of the closed upper end of thecup 37, and the other end thereof bears against a washer all, which isadjustably positioned relative to the rod 36 for varying the tension onthe spring, by a nut 56 which is threaded on the lower end of rod 35.The cup member 31 is welded or otherwise rigidly secured to the bracket22 and positioned so that the axis of the rod 36 is offset or in spacedrelation to the axis of pivotal support of the bell crank member 29.

In the operation of this device suitable tension is placed on the spring38 by the nut 40, and the motor unit is connected to the arm 25 of thebell crank in proper relation to the length of the bristles of the brushif! by adjustment of the turnbuckle 29. In this position the roller 35is near the left hand end of the cam slot 34. As the bristles wear offof the brushes during the normal use thereof, the motor unit and brushholding unit, lowers toward the floor, at which time the bell crank isrotated clockwise, as viewed in the drawing, whereupon the cam slot 34raises the rod 3i; and further compresses the compression spring 38.

Although but one specific embodiment of this invention has been hereinshown and described, it will be understood that numerous details of theconstruction shown may be altered or omitted without departing from thespirit of this invention as defined by the following claims.

What is claimed is:

1. In floor scrubbing machine, a frame, a scrubbing brush movablyconnected to said frame and tending to move downwardly by force ofgravity, a weight balancing device for said brush mounted on said frame,including a bell crank pivotally supported by said frame, a linkconnecting one arm of said bell crank to said brush, the other arm ofsaid bell crank having a cam slot therein, and yielding means actingbetween said frame and cam slot tending to rotate said bell crank in adirection to counterbalance the weight of said brush.

2. In a floor scrubbing machine, a frame, a scrubbing brush movablyconnected to said frame and tending to move downwardly by force ofgravity, a weight balancing device for said brush mounted on said frame,including a bell crank pivotally supported by said frame, an adjustablelink connecting one arm of said bell crank to said brush, the other armof said bell crank having a cam slot therein, and yielding means actingbetween said frame and cam slot tending to 1'0- tate said bell crank ina direction to counterbalance the weight of said brush.

3. In a floor scrubbing machine, a frame, a scrub brush pivotallyconnected to said frame so as to tend to swing downwardly by force ofgravity, a device mounted on said frame for counterbalancing the weightof said brush, said device including a bell crank pivoted on said frame,a link connecting one arm of said bell crank to said brush, the otherarm of said bell crank having an arcuate slot therein, the center fromwhich said slot is formed being offset with respect tothe axis ofpivotal support of said bell crank, anti yielding means acting betweensaid frame and cam slot tending to rotate said bell crank in a directionto counterbalance the weight of said brush.

4. In a floor scrubbing machine, a frame, a scrub brush pivotallyconnected to said frame so as to tend to swing downwardly by force ofgravity, a device mounted on said frame for counterbalancing the weightof said brush, said device including a bell crank pivoted on said frame,a link connecting one arm of said bell crank to said brush, the otherarm of said bell cranl: having an arcuate slot therein, the center fromwhich said slot is formed being offset with respect to the axis ofpivotal support of said bell crank, a rod slldably mounted on said frameand having axial movement relative thereto, a roller pivoted on said rodand embraced by the side walls of said cam slot, and a helicalcompression spring bearing between said frame and said rod for causingsaid roller .to bear against a wall of said cam slot and thereby tend torotate said bell crank in a direction to counterbalance the weight ofsaid brush.

5. In a floor scrubbing machine, a frame, a scrub brush pivotallyconnected to said. frame so as to tend to swing. downwardly by force ofgravity, a device mounted on said frame for counterbalancing the weightof said brush, said device including a bell crank pivoted on said frame,a link connecting one arm of said bell crank to said brush, the otherarm of said hell crank having an arcuate slot therein, the center. fromwhich said slot is formed being offset with respect to the axis ofpivotal support of said bell crank, a rod slidably mounted on said frameand having axial movement relative thereto, the axis of said rod beingoffset with respect to the center of pivotal connection of said bellcrank and with respect to the center about which said cam slot isformed, a roller pivoted on said rod and embraced by the side walls ofsaid cam slot, and a helical compression spring bearing between saidframe and said rod for causing said roller to bear against a wall ofsaid cam slotand thereby tend to rotate said bell crank in a directionto counterbalance the weight of said brush.

IRA C. SARBER.

